How would you determine the maximum stroke and rod length for a B16 or B18 block?

I am thinking about building a motor and wanted to increase the stroke and bore without getting away from the ideal 1.75 r/s ratio.

Some combos I've come up with so far:

3.433" Stroke out of B18A1
5.967" Rod
= 1.738 R/S ratio

3.205" Stroke out of B17A1
5.531" Rod
= 1.725 R/S ratio

3.409" Stroke
5.967" Rod
=1.75

I can't find anything on the web describing any max stroke and rod lengths, so I don't know whether the first two would work. There isn't a crank available at 3.409" stroke, so it would have to be custom. Obviously, I'd prefer the first one for torque purposes and because it is closer to 1.75 r/s ratio, as well as being factory. And cheaper

 

rod lenghts:

B16: 134mm
B17: 131.87mm
B18a/b B20b/z: 137mm
B18c: 137.9mm
B20a: 142.75mm
B21a: 141.7mm


stroke:
b16: 77mm
b17: 81.4mm
b18a/b: 89mm
b18c: 87.2mm

To get better rs from lets say a b18a/b you would have to get a longer rod, since there arent many aftermarket cranks. and with stock stroke it would be impossible to bring a b18 to a 1.7 ratio since you would have to us at least a 151/2 mm rod and you would have to use a custom piston that has a higher wrist pin and would have to have less compression height(from 29.972 mm to 15.972 mm). Unless of course you get a deck plate.
get the point? you cant just make up #'s and plug themn in; you have to work with the parts that you have available..

 

what are the rpms you are seeking with this??

and btw http://www.scatcrankshafts.com....html

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by mmuller &raquo;</TD></TR><TR><TD CLASS="quote">rod lenghts:

B16: 134mm
B17: 131.87mm
B18a/b B20b/z: 137mm
B18c: 137.9mm
B20a: 142.75mm
B21a: 141.7mm


stroke:
b16: 77mm
b17: 81.4mm
b18a/b: 89mm
b18c: 87.2mm

..</TD></TR></TABLE>

Where did you get these numbers? I'm only asking, because they are, for the most part, lower than the numbers I have for stock stroke and rod length. In which case, they are lower than any of the available 'stroker kits' for the B16, B18, and B20s. If these numbers are more accurate than mine, I'd rather be working with those.

As far as the numbers, the numbers I used are from easily available parts...which is why I'm checking clearance and quench issues. They also aren't that different from many of the stroker kits available, the numbers are just distributed differently to bring up the r/s ratio.

To answer JSMC, I want the r/s balance mostly for longevity but also for power. I'd prefer the taller stroke for torgue benefits, simply because torque in these small 4 cyl sucks . And since I'll be doing this in stages, I have to address these issues early on.

Okay, basically, I'm looking for better torque distribution (from taller stroke) without the added unreliability. I also want to keep the compression down for later forced induction applications.